This invention relates to a corrosion resistant apparatus for processing substrates, such as semiconductor wafers.
In many types of manufacturing processes, substrates are processed in corrosive process environments. For example, in semiconductor fabrication processes, corrosive process gases are used to deposit material upon, etch, or clean semiconductor wafers. Semiconductor processes are typically carried out in an enclosed process chamber containing metal, ceramic, glass and polymer components. Metal components fabricated from stainless steel, aluminum or high temperature alloys such as "INCONEL," are typically used for holding, loading and positioning substrates in the chamber, for chamber walls, and for controlling process gas flow in and out of the chamber. In addition, ceramic components, such as quartz guards and high temperature chucks, are also used in the chamber. The process chamber and components therein often corrode in corrosive process gas, particularly in reactive halogen gases and plasmas. For example, a plasma of nitrogen trifluoride (which is used to clean process chambers), contains reactive fluorine species that readily corrode aluminum chambers and components.
Corrosion of the components and process chamber by the corrosive process gas limits the lifetime of the apparatus and increases apparatus downtime. The corroded components can also flake off and form contaminant particles which deposit on the substrate. It is difficult to non-destructively detect such contamination during the initial stages of processing the wafer. Thus, it is only in the final stages of the manufacturing process, when a fully processed semiconductor wafer is often worth at least $50,000, that the contaminants are discovered, and the entire wafer is rejected.
Thus, there is a need for a corrosion resistant apparatus and processing components that resist corrosion when exposed to corrosive process gas, and in particular corrosive plasmas. There is also a need for a corrosion resistant apparatus that does not corrode and flake off to form contaminants that deposit on the substrates. There is also a need for a corrosion resistant apparatus that can be easily and inexpensively fabricated.